using System;
using System.Threading;
using System.Collections.Generic;
using System.IO;

namespace PickGold.Zip
{
	/// <summary>
	///   Provides a stream metaphor for generating zip files.
	/// </summary>
	///
	/// <remarks>
	/// <para>
	///   This class writes zip files, as defined in the <see
	///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">specification
	///   for zip files described by PKWare</see>.  The compression for this
	///   implementation is provided by a managed-code version of Zlib, included with
	///   DotNetZip in the classes in the PickGold.Zlib namespace.
	/// </para>
	///
	/// <para>
	///   This class provides an alternative programming model to the one enabled by the
	///   <see cref="ZipFile"/> class. Use this when creating zip files, as an
	///   alternative to the <see cref="ZipFile"/> class, when you would like to use a
	///   <c>Stream</c> type to write the zip file.
	/// </para>
	///
	/// <para>
	///   Both the <c>ZipOutputStream</c> class and the <c>ZipFile</c> class can be used
	///   to create zip files. Both of them support many of the common zip features,
	///   including Unicode, different compression levels, and ZIP64.   They provide
	///   very similar performance when creating zip files.
	/// </para>
	///
	/// <para>
	///   The <c>ZipFile</c> class is generally easier to use than
	///   <c>ZipOutputStream</c> and should be considered a higher-level interface.  For
	///   example, when creating a zip file via calls to the <c>PutNextEntry()</c> and
	///   <c>Write()</c> methods on the <c>ZipOutputStream</c> class, the caller is
	///   responsible for opening the file, reading the bytes from the file, writing
	///   those bytes into the <c>ZipOutputStream</c>, setting the attributes on the
	///   <c>ZipEntry</c>, and setting the created, last modified, and last accessed
	///   timestamps on the zip entry. All of these things are done automatically by a
	///   call to <see cref="ZipFile.AddFile(string,string)">ZipFile.AddFile()</see>.
	///   For this reason, the <c>ZipOutputStream</c> is generally recommended for use
	///   only when your application emits arbitrary data, not necessarily data from a
	///   filesystem file, directly into a zip file, and does so using a <c>Stream</c>
	///   metaphor.
	/// </para>
	///
	/// <para>
	///   Aside from the differences in programming model, there are other
	///   differences in capability between the two classes.
	/// </para>
	///
	/// <list type="bullet">
	///   <item>
	///     <c>ZipFile</c> can be used to read and extract zip files, in addition to
	///     creating zip files. <c>ZipOutputStream</c> cannot read zip files. If you want
	///     to use a stream to read zip files, check out the <see cref="ZipInputStream"/> class.
	///   </item>
	///
	///   <item>
	///     <c>ZipOutputStream</c> does not support the creation of segmented or spanned
	///     zip files.
	///   </item>
	///
	///   <item>
	///     <c>ZipOutputStream</c> cannot produce a self-extracting archive.
	///   </item>
	/// </list>
	///
	/// <para>
	///   Be aware that the <c>ZipOutputStream</c> class implements the <see
	///   cref="System.IDisposable"/> interface.  In order for
	///   <c>ZipOutputStream</c> to produce a valid zip file, you use use it within
	///   a using clause (<c>Using</c> in VB), or call the <c>Dispose()</c> method
	///   explicitly.  See the examples for how to employ a using clause.
	/// </para>
	///
	/// <para>
	///   Also, a note regarding compression performance: On the desktop .NET
	///   Framework, DotNetZip can use a multi-threaded compression implementation
	///   that provides significant speed increases on large files, over 300k or so,
	///   at the cost of increased memory use at runtime.  (The output of the
	///   compression is almost exactly the same size).  But, the multi-threaded
	///   approach incurs a performance hit on smaller files. There's no way for the
	///   ZipOutputStream to know whether parallel compression will be beneficial,
	///   because the ZipOutputStream does not know how much data you will write
	///   through the stream.  You may wish to set the <see
	///   cref="ParallelDeflateThreshold"/> property to zero, if you are compressing
	///   large files through <c>ZipOutputStream</c>.  This will cause parallel
	///   compression to be used, always.
	/// </para>
	/// </remarks>
	public class ZipOutputStream : Stream
	{
		/// <summary>
		///   Create a ZipOutputStream, wrapping an existing stream.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The <see cref="ZipFile"/> class is generally easier to use when creating
		///   zip files. The ZipOutputStream offers a different metaphor for creating a
		///   zip file, based on the <see cref="System.IO.Stream"/> class.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="stream">
		/// The stream to wrap. It must be writable. This stream will be closed at
		/// the time the ZipOutputStream is closed.
		/// </param>
		///
		/// <example>
		///
		///   This example shows how to create a zip file, using the
		///   ZipOutputStream class.
		///
		/// <code lang="C#">
		/// private void Zipup()
		/// {
		///     if (filesToZip.Count == 0)
		///     {
		///         System.Console.WriteLine("Nothing to do.");
		///         return;
		///     }
		///
		///     using (var raw = File.Open(_outputFileName, FileMode.Create, FileAccess.ReadWrite ))
		///     {
		///         using (var output= new ZipOutputStream(raw))
		///         {
		///             output.Password = "VerySecret!";
		///             output.Encryption = EncryptionAlgorithm.WinZipAes256;
		///
		///             foreach (string inputFileName in filesToZip)
		///             {
		///                 System.Console.WriteLine("file: {0}", inputFileName);
		///
		///                 output.PutNextEntry(inputFileName);
		///                 using (var input = File.Open(inputFileName, FileMode.Open, FileAccess.Read, FileShare.Read | FileShare.Write ))
		///                 {
		///                     byte[] buffer= new byte[2048];
		///                     int n;
		///                     while ((n= input.Read(buffer,0,buffer.Length)) > 0)
		///                     {
		///                         output.Write(buffer,0,n);
		///                     }
		///                 }
		///             }
		///         }
		///     }
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Private Sub Zipup()
		///     Dim outputFileName As String = "XmlData.zip"
		///     Dim filesToZip As String() = Directory.GetFiles(".", "*.xml")
		///     If (filesToZip.Length = 0) Then
		///         Console.WriteLine("Nothing to do.")
		///     Else
		///         Using raw As FileStream = File.Open(outputFileName, FileMode.Create, FileAccess.ReadWrite)
		///             Using output As ZipOutputStream = New ZipOutputStream(raw)
		///                 output.Password = "VerySecret!"
		///                 output.Encryption = EncryptionAlgorithm.WinZipAes256
		///                 Dim inputFileName As String
		///                 For Each inputFileName In filesToZip
		///                     Console.WriteLine("file: {0}", inputFileName)
		///                     output.PutNextEntry(inputFileName)
		///                     Using input As FileStream = File.Open(inputFileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)
		///                         Dim n As Integer
		///                         Dim buffer As Byte() = New Byte(2048) {}
		///                         Do While (n = input.Read(buffer, 0, buffer.Length) > 0)
		///                             output.Write(buffer, 0, n)
		///                         Loop
		///                     End Using
		///                 Next
		///             End Using
		///         End Using
		///     End If
		/// End Sub
		/// </code>
		/// </example>
		public ZipOutputStream(Stream stream) : this(stream, false) { }


		/// <summary>
		///   Create a ZipOutputStream that writes to a filesystem file.
		/// </summary>
		///
		/// <remarks>
		///   The <see cref="ZipFile"/> class is generally easier to use when creating
		///   zip files. The ZipOutputStream offers a different metaphor for creating a
		///   zip file, based on the <see cref="System.IO.Stream"/> class.
		/// </remarks>
		///
		/// <param name="fileName">
		///   The name of the zip file to create.
		/// </param>
		///
		/// <example>
		///
		///   This example shows how to create a zip file, using the
		///   ZipOutputStream class.
		///
		/// <code lang="C#">
		/// private void Zipup()
		/// {
		///     if (filesToZip.Count == 0)
		///     {
		///         System.Console.WriteLine("Nothing to do.");
		///         return;
		///     }
		///
		///     using (var output= new ZipOutputStream(outputFileName))
		///     {
		///         output.Password = "VerySecret!";
		///         output.Encryption = EncryptionAlgorithm.WinZipAes256;
		///
		///         foreach (string inputFileName in filesToZip)
		///         {
		///             System.Console.WriteLine("file: {0}", inputFileName);
		///
		///             output.PutNextEntry(inputFileName);
		///             using (var input = File.Open(inputFileName, FileMode.Open, FileAccess.Read,
		///                                          FileShare.Read | FileShare.Write ))
		///             {
		///                 byte[] buffer= new byte[2048];
		///                 int n;
		///                 while ((n= input.Read(buffer,0,buffer.Length)) > 0)
		///                 {
		///                     output.Write(buffer,0,n);
		///                 }
		///             }
		///         }
		///     }
		/// }
		/// </code>
		///
		/// <code lang="VB">
		/// Private Sub Zipup()
		///     Dim outputFileName As String = "XmlData.zip"
		///     Dim filesToZip As String() = Directory.GetFiles(".", "*.xml")
		///     If (filesToZip.Length = 0) Then
		///         Console.WriteLine("Nothing to do.")
		///     Else
		///         Using output As ZipOutputStream = New ZipOutputStream(outputFileName)
		///             output.Password = "VerySecret!"
		///             output.Encryption = EncryptionAlgorithm.WinZipAes256
		///             Dim inputFileName As String
		///             For Each inputFileName In filesToZip
		///                 Console.WriteLine("file: {0}", inputFileName)
		///                 output.PutNextEntry(inputFileName)
		///                 Using input As FileStream = File.Open(inputFileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)
		///                     Dim n As Integer
		///                     Dim buffer As Byte() = New Byte(2048) {}
		///                     Do While (n = input.Read(buffer, 0, buffer.Length) > 0)
		///                         output.Write(buffer, 0, n)
		///                     Loop
		///                 End Using
		///             Next
		///         End Using
		///     End If
		/// End Sub
		/// </code>
		/// </example>
		public ZipOutputStream(String fileName)
		{
			Stream stream = File.Open(fileName, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
			_Init(stream, false, fileName);
		}


		/// <summary>
		///   Create a ZipOutputStream.
		/// </summary>
		///
		/// <remarks>
		///   See the documentation for the <see
		///   cref="ZipOutputStream(Stream)">ZipOutputStream(Stream)</see>
		///   constructor for an example.
		/// </remarks>
		///
		/// <param name="stream">
		///   The stream to wrap. It must be writable.
		/// </param>
		///
		/// <param name="leaveOpen">
		///   true if the application would like the stream
		///   to remain open after the <c>ZipOutputStream</c> has been closed.
		/// </param>
		public ZipOutputStream(Stream stream, bool leaveOpen)
		{
			_Init(stream, leaveOpen, null);
		}

		private void _Init(Stream stream, bool leaveOpen, string name)
		{
			// workitem 9307
			_outputStream = stream.CanRead ? stream : new CountingStream(stream);
			CompressionLevel = PickGold.Zlib.CompressionLevel.Default;
			CompressionMethod = PickGold.Zip.CompressionMethod.Deflate;
			_encryption = EncryptionAlgorithm.None;
			_entriesWritten = new Dictionary<String, ZipEntry>(StringComparer.Ordinal);
			_zip64 = Zip64Option.Never;
			_leaveUnderlyingStreamOpen = leaveOpen;
			Strategy = PickGold.Zlib.CompressionStrategy.Default;
			_name = name ?? "(stream)";
#if !NETCF
			ParallelDeflateThreshold = -1L;
#endif
		}


		/// <summary>Provides a string representation of the instance.</summary>
		/// <remarks>
		///   <para>
		///     This can be useful for debugging purposes.
		///   </para>
		/// </remarks>
		/// <returns>a string representation of the instance.</returns>
		public override String ToString()
		{
			return String.Format("ZipOutputStream::{0}(leaveOpen({1})))", _name, _leaveUnderlyingStreamOpen);
		}


		/// <summary>
		///   Sets the password to be used on the <c>ZipOutputStream</c> instance.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   When writing a zip archive, this password is applied to the entries, not
		///   to the zip archive itself. It applies to any <c>ZipEntry</c> subsequently
		///   written to the <c>ZipOutputStream</c>.
		/// </para>
		///
		/// <para>
		///   Using a password does not encrypt or protect the "directory" of the
		///   archive - the list of entries contained in the archive.  If you set the
		///   <c>Password</c> property, the password actually applies to individual
		///   entries that are added to the archive, subsequent to the setting of this
		///   property.  The list of filenames in the archive that is eventually created
		///   will appear in clear text, but the contents of the individual files are
		///   encrypted.  This is how Zip encryption works.
		/// </para>
		///
		/// <para>
		///   If you set this property, and then add a set of entries to the archive via
		///   calls to <c>PutNextEntry</c>, then each entry is encrypted with that
		///   password.  You may also want to change the password between adding
		///   different entries. If you set the password, add an entry, then set the
		///   password to <c>null</c> (<c>Nothing</c> in VB), and add another entry, the
		///   first entry is encrypted and the second is not.
		/// </para>
		///
		/// <para>
		///   When setting the <c>Password</c>, you may also want to explicitly set the <see
		///   cref="Encryption"/> property, to specify how to encrypt the entries added
		///   to the ZipFile.  If you set the <c>Password</c> to a non-null value and do not
		///   set <see cref="Encryption"/>, then PKZip 2.0 ("Weak") encryption is used.
		///   This encryption is relatively weak but is very interoperable. If
		///   you set the password to a <c>null</c> value (<c>Nothing</c> in VB),
		///   <c>Encryption</c> is reset to None.
		/// </para>
		///
		/// <para>
		///   Special case: if you wrap a ZipOutputStream around a non-seekable stream,
		///   and use encryption, and emit an entry of zero bytes, the <c>Close()</c> or
		///   <c>PutNextEntry()</c> following the entry will throw an exception.
		/// </para>
		///
		/// </remarks>
		public String Password
		{
			set
			{
				if (_disposed)
				{
					_exceptionPending = true;
					throw new System.InvalidOperationException("The stream has been closed.");
				}

				_password = value;
				if (_password == null)
				{
					_encryption = EncryptionAlgorithm.None;
				}
				else if (_encryption == EncryptionAlgorithm.None)
				{
					_encryption = EncryptionAlgorithm.PkzipWeak;
				}
			}
		}


		/// <summary>
		///   The Encryption to use for entries added to the <c>ZipOutputStream</c>.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The specified Encryption is applied to the entries subsequently
		///   written to the <c>ZipOutputStream</c> instance.
		/// </para>
		///
		/// <para>
		///   If you set this to something other than
		///   EncryptionAlgorithm.None, you will also need to set the
		///   <see cref="Password"/> to a non-null, non-empty value in
		///   order to actually get encryption on the entry.
		/// </para>
		///
		/// </remarks>
		///
		/// <seealso cref="Password">ZipOutputStream.Password</seealso>
		/// <seealso cref="PickGold.Zip.ZipEntry.Encryption">ZipEntry.Encryption</seealso>
		public EncryptionAlgorithm Encryption
		{
			get
			{
				return _encryption;
			}
			set
			{
				if (_disposed)
				{
					_exceptionPending = true;
					throw new System.InvalidOperationException("The stream has been closed.");
				}
				if (value == EncryptionAlgorithm.Unsupported)
				{
					_exceptionPending = true;
					throw new InvalidOperationException("You may not set Encryption to that value.");
				}
				_encryption = value;
			}
		}


		/// <summary>
		///   Size of the work buffer to use for the ZLIB codec during compression.
		/// </summary>
		///
		/// <remarks>
		///   Setting this may affect performance.  For larger files, setting this to a
		///   larger size may improve performance, but I'm not sure.  Sorry, I don't
		///   currently have good recommendations on how to set it.  You can test it if
		///   you like.
		/// </remarks>
		public int CodecBufferSize
		{
			get;
			set;
		}


		/// <summary>
		///   The compression strategy to use for all entries.
		/// </summary>
		///
		/// <remarks>
		///   Set the Strategy used by the ZLIB-compatible compressor, when compressing
		///   data for the entries in the zip archive. Different compression strategies
		///   work better on different sorts of data. The strategy parameter can affect
		///   the compression ratio and the speed of compression but not the correctness
		///   of the compresssion.  For more information see <see
		///   cref="PickGold.Zlib.CompressionStrategy "/>.
		/// </remarks>
		public PickGold.Zlib.CompressionStrategy Strategy
		{
			get;
			set;
		}


		/// <summary>
		///   The type of timestamp attached to the ZipEntry.
		/// </summary>
		///
		/// <remarks>
		///   Set this in order to specify the kind of timestamp that should be emitted
		///   into the zip file for each entry.
		/// </remarks>
		public ZipEntryTimestamp Timestamp
		{
			get
			{
				return _timestamp;
			}
			set
			{
				if (_disposed)
				{
					_exceptionPending = true;
					throw new System.InvalidOperationException("The stream has been closed.");
				}
				_timestamp = value;
			}
		}


		/// <summary>
		///   Sets the compression level to be used for entries subsequently added to
		///   the zip archive.
		/// </summary>
		///
		/// <remarks>
		///  <para>
		///    Varying the compression level used on entries can affect the
		///    size-vs-speed tradeoff when compression and decompressing data streams
		///    or files.
		///  </para>
		///
		///  <para>
		///    As with some other properties on the <c>ZipOutputStream</c> class, like <see
		///    cref="Password"/>, and <see cref="Encryption"/>,
		///    setting this property on a <c>ZipOutputStream</c>
		///    instance will cause the specified <c>CompressionLevel</c> to be used on all
		///    <see cref="ZipEntry"/> items that are subsequently added to the
		///    <c>ZipOutputStream</c> instance.
		///  </para>
		///
		///  <para>
		///    If you do not set this property, the default compression level is used,
		///    which normally gives a good balance of compression efficiency and
		///    compression speed.  In some tests, using <c>BestCompression</c> can
		///    double the time it takes to compress, while delivering just a small
		///    increase in compression efficiency.  This behavior will vary with the
		///    type of data you compress.  If you are in doubt, just leave this setting
		///    alone, and accept the default.
		///  </para>
		/// </remarks>
		public PickGold.Zlib.CompressionLevel CompressionLevel
		{
			get;
			set;
		}

		/// <summary>
		///   The compression method used on each entry added to the ZipOutputStream.
		/// </summary>
		public PickGold.Zip.CompressionMethod CompressionMethod
		{
			get;
			set;
		}


		/// <summary>
		///   A comment attached to the zip archive.
		/// </summary>
		///
		/// <remarks>
		///
		/// <para>
		///   The application sets this property to specify a comment to be embedded
		///   into the generated zip archive.
		/// </para>
		///
		/// <para>
		///   According to <see
		///   href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">PKWARE's
		///   zip specification</see>, the comment is not encrypted, even if there is a
		///   password set on the zip file.
		/// </para>
		///
		/// <para>
		///   The specification does not describe how to indicate the encoding used
		///   on a comment string. Many "compliant" zip tools and libraries use
		///   IBM437 as the code page for comments; DotNetZip, too, follows that
		///   practice.  On the other hand, there are situations where you want a
		///   Comment to be encoded with something else, for example using code page
		///   950 "Big-5 Chinese". To fill that need, DotNetZip will encode the
		///   comment following the same procedure it follows for encoding
		///   filenames: (a) if <see cref="AlternateEncodingUsage"/> is
		///   <c>Never</c>, it uses the default encoding (IBM437). (b) if <see
		///   cref="AlternateEncodingUsage"/> is <c>Always</c>, it always uses the
		///   alternate encoding (<see cref="AlternateEncoding"/>). (c) if <see
		///   cref="AlternateEncodingUsage"/> is <c>AsNecessary</c>, it uses the
		///   alternate encoding only if the default encoding is not sufficient for
		///   encoding the comment - in other words if decoding the result does not
		///   produce the original string.  This decision is taken at the time of
		///   the call to <c>ZipFile.Save()</c>.
		/// </para>
		///
		/// </remarks>
		public string Comment
		{
			get { return _comment; }
			set
			{
				if (_disposed)
				{
					_exceptionPending = true;
					throw new System.InvalidOperationException("The stream has been closed.");
				}
				_comment = value;
			}
		}



		/// <summary>
		///   Specify whether to use ZIP64 extensions when saving a zip archive.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   The default value for the property is <see
		///   cref="Zip64Option.Never"/>. <see cref="Zip64Option.AsNecessary"/> is
		///   safest, in the sense that you will not get an Exception if a
		///   pre-ZIP64 limit is exceeded.
		/// </para>
		///
		/// <para>
		///   You must set this property before calling <c>Write()</c>.
		/// </para>
		///
		/// </remarks>
		public Zip64Option EnableZip64
		{
			get
			{
				return _zip64;
			}
			set
			{
				if (_disposed)
				{
					_exceptionPending = true;
					throw new System.InvalidOperationException("The stream has been closed.");
				}
				_zip64 = value;
			}
		}


		/// <summary>
		///   Indicates whether ZIP64 extensions were used when saving the zip archive.
		/// </summary>
		///
		/// <remarks>
		///   The value is defined only after the <c>ZipOutputStream</c> has been closed.
		/// </remarks>
		public bool OutputUsedZip64
		{
			get
			{
				return _anyEntriesUsedZip64 || _directoryNeededZip64;
			}
		}


		/// <summary>
		///   Whether the ZipOutputStream should use case-insensitive comparisons when
		///   checking for uniqueness of zip entries.
		/// </summary>
		///
		/// <remarks>
		///   <para>
		///   Though the zip specification doesn't prohibit zipfiles with duplicate
		///   entries, Sane zip files have no duplicates, and the DotNetZip library
		///   cannot create zip files with duplicate entries. If an application attempts
		///   to call <see cref="PutNextEntry(String)"/> with a name that duplicates one
		///   already used within the archive, the library will throw an Exception.
		///   </para>
		///   <para>
		///   This property allows the application to specify whether the
		///   ZipOutputStream instance considers ordinal case when checking for
		///   uniqueness of zip entries.
		///   </para>
		/// </remarks>
		public bool IgnoreCase
		{
			get
			{
				return !_DontIgnoreCase;
			}

			set
			{
				_DontIgnoreCase = !value;
			}

		}


		/// <summary>
		///   Indicates whether to encode entry filenames and entry comments using
		///   Unicode (UTF-8).
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   <see href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">The
		///   PKWare zip specification</see> provides for encoding file names and file
		///   comments in either the IBM437 code page, or in UTF-8.  This flag selects
		///   the encoding according to that specification.  By default, this flag is
		///   false, and filenames and comments are encoded into the zip file in the
		///   IBM437 codepage.  Setting this flag to true will specify that filenames
		///   and comments that cannot be encoded with IBM437 will be encoded with
		///   UTF-8.
		/// </para>
		///
		/// <para>
		///   Zip files created with strict adherence to the PKWare specification with
		///   respect to UTF-8 encoding can contain entries with filenames containing
		///   any combination of Unicode characters, including the full range of
		///   characters from Chinese, Latin, Hebrew, Greek, Cyrillic, and many other
		///   alphabets.  However, because at this time, the UTF-8 portion of the PKWare
		///   specification is not broadly supported by other zip libraries and
		///   utilities, such zip files may not be readable by your favorite zip tool or
		///   archiver. In other words, interoperability will decrease if you set this
		///   flag to true.
		/// </para>
		///
		/// <para>
		///   In particular, Zip files created with strict adherence to the PKWare
		///   specification with respect to UTF-8 encoding will not work well with
		///   Explorer in Windows XP or Windows Vista, because Windows compressed
		///   folders, as far as I know, do not support UTF-8 in zip files.  Vista can
		///   read the zip files, but shows the filenames incorrectly. Unpacking from
		///   Windows Vista Explorer will result in filenames that have rubbish
		///   characters in place of the high-order UTF-8 bytes.
		/// </para>
		///
		/// <para>
		///   Also, zip files that use UTF-8 encoding will not work well with Java
		///   applications that use the java.util.zip classes, as of v5.0 of the Java
		///   runtime. The Java runtime does not correctly implement the PKWare
		///   specification in this regard.
		/// </para>
		///
		/// <para>
		///   As a result, we have the unfortunate situation that "correct" behavior by
		///   the DotNetZip library with regard to Unicode encoding of filenames during
		///   zip creation will result in zip files that are readable by strictly
		///   compliant and current tools (for example the most recent release of the
		///   commercial WinZip tool); but these zip files will not be readable by
		///   various other tools or libraries, including Windows Explorer.
		/// </para>
		///
		/// <para>
		///   The DotNetZip library can read and write zip files with UTF8-encoded
		///   entries, according to the PKware spec.  If you use DotNetZip for both
		///   creating and reading the zip file, and you use UTF-8, there will be no
		///   loss of information in the filenames. For example, using a self-extractor
		///   created by this library will allow you to unpack files correctly with no
		///   loss of information in the filenames.
		/// </para>
		///
		/// <para>
		///   If you do not set this flag, it will remain false.  If this flag is false,
		///   the <c>ZipOutputStream</c> will encode all filenames and comments using
		///   the IBM437 codepage.  This can cause "loss of information" on some
		///   filenames, but the resulting zipfile will be more interoperable with other
		///   utilities. As an example of the loss of information, diacritics can be
		///   lost.  The o-tilde character will be down-coded to plain o.  The c with a
		///   cedilla (Unicode 0xE7) used in Portugese will be downcoded to a c.
		///   Likewise, the O-stroke character (Unicode 248), used in Danish and
		///   Norwegian, will be down-coded to plain o. Chinese characters cannot be
		///   represented in codepage IBM437; when using the default encoding, Chinese
		///   characters in filenames will be represented as ?. These are all examples
		///   of "information loss".
		/// </para>
		///
		/// <para>
		///   The loss of information associated to the use of the IBM437 encoding is
		///   inconvenient, and can also lead to runtime errors. For example, using
		///   IBM437, any sequence of 4 Chinese characters will be encoded as ????.  If
		///   your application creates a <c>ZipOutputStream</c>, does not set the
		///   encoding, then adds two files, each with names of four Chinese characters
		///   each, this will result in a duplicate filename exception.  In the case
		///   where you add a single file with a name containing four Chinese
		///   characters, the zipfile will save properly, but extracting that file
		///   later, with any zip tool, will result in an error, because the question
		///   mark is not legal for use within filenames on Windows.  These are just a
		///   few examples of the problems associated to loss of information.
		/// </para>
		///
		/// <para>
		///   This flag is independent of the encoding of the content within the entries
		///   in the zip file. Think of the zip file as a container - it supports an
		///   encoding.  Within the container are other "containers" - the file entries
		///   themselves.  The encoding within those entries is independent of the
		///   encoding of the zip archive container for those entries.
		/// </para>
		///
		/// <para>
		///   Rather than specify the encoding in a binary fashion using this flag, an
		///   application can specify an arbitrary encoding via the <see
		///   cref="ProvisionalAlternateEncoding"/> property.  Setting the encoding
		///   explicitly when creating zip archives will result in non-compliant zip
		///   files that, curiously, are fairly interoperable.  The challenge is, the
		///   PKWare specification does not provide for a way to specify that an entry
		///   in a zip archive uses a code page that is neither IBM437 nor UTF-8.
		///   Therefore if you set the encoding explicitly when creating a zip archive,
		///   you must take care upon reading the zip archive to use the same code page.
		///   If you get it wrong, the behavior is undefined and may result in incorrect
		///   filenames, exceptions, stomach upset, hair loss, and acne.
		/// </para>
		/// </remarks>
		/// <seealso cref="ProvisionalAlternateEncoding"/>
		[Obsolete("Beginning with v1.9.1.6 of DotNetZip, this property is obsolete. It will be removed in a future version of the library. Use AlternateEncoding and AlternateEncodingUsage instead.")]
		public bool UseUnicodeAsNecessary
		{
			get
			{
				return (_alternateEncoding == System.Text.Encoding.UTF8) &&
					(AlternateEncodingUsage == ZipOption.AsNecessary);
			}
			set
			{
				if (value)
				{
					_alternateEncoding = System.Text.Encoding.UTF8;
					_alternateEncodingUsage = ZipOption.AsNecessary;

				}
				else
				{
					_alternateEncoding = PickGold.Zip.ZipOutputStream.DefaultEncoding;
					_alternateEncodingUsage = ZipOption.Never;
				}
			}
		}


		/// <summary>
		///   The text encoding to use when emitting entries into the zip archive, for
		///   those entries whose filenames or comments cannot be encoded with the
		///   default (IBM437) encoding.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   In <see href="http://www.pkware.com/documents/casestudies/APPNOTE.TXT">its
		///   zip specification</see>, PKWare describes two options for encoding
		///   filenames and comments: using IBM437 or UTF-8.  But, some archiving tools
		///   or libraries do not follow the specification, and instead encode
		///   characters using the system default code page.  For example, WinRAR when
		///   run on a machine in Shanghai may encode filenames with the Big-5 Chinese
		///   (950) code page.  This behavior is contrary to the Zip specification, but
		///   it occurs anyway.
		/// </para>
		///
		/// <para>
		///   When using DotNetZip to write zip archives that will be read by one of
		///   these other archivers, set this property to specify the code page to use
		///   when encoding the <see cref="ZipEntry.FileName"/> and <see
		///   cref="ZipEntry.Comment"/> for each <c>ZipEntry</c> in the zip file, for
		///   values that cannot be encoded with the default codepage for zip files,
		///   IBM437.  This is why this property is "provisional".  In all cases, IBM437
		///   is used where possible, in other words, where no loss of data would
		///   result. It is possible, therefore, to have a given entry with a
		///   <c>Comment</c> encoded in IBM437 and a <c>FileName</c> encoded with the
		///   specified "provisional" codepage.
		/// </para>
		///
		/// <para>
		///   Be aware that a zip file created after you've explicitly set the
		///   <c>ProvisionalAlternateEncoding</c> property to a value other than
		///   IBM437 may not be compliant to the PKWare specification, and may not be
		///   readable by compliant archivers.  On the other hand, many (most?)
		///   archivers are non-compliant and can read zip files created in arbitrary
		///   code pages.  The trick is to use or specify the proper codepage when
		///   reading the zip.
		/// </para>
		///
		/// <para>
		///   When creating a zip archive using this library, it is possible to change
		///   the value of <c>ProvisionalAlternateEncoding</c> between each entry you
		///   add, and between adding entries and the call to <c>Close()</c>. Don't do
		///   this. It will likely result in a zipfile that is not readable.  For best
		///   interoperability, either leave <c>ProvisionalAlternateEncoding</c>
		///   alone, or specify it only once, before adding any entries to the
		///   <c>ZipOutputStream</c> instance.  There is one exception to this
		///   recommendation, described later.
		/// </para>
		///
		/// <para>
		///   When using an arbitrary, non-UTF8 code page for encoding, there is no
		///   standard way for the creator application - whether DotNetZip, WinZip,
		///   WinRar, or something else - to formally specify in the zip file which
		///   codepage has been used for the entries. As a result, readers of zip files
		///   are not able to inspect the zip file and determine the codepage that was
		///   used for the entries contained within it.  It is left to the application
		///   or user to determine the necessary codepage when reading zip files encoded
		///   this way.  If you use an incorrect codepage when reading a zipfile, you
		///   will get entries with filenames that are incorrect, and the incorrect
		///   filenames may even contain characters that are not legal for use within
		///   filenames in Windows. Extracting entries with illegal characters in the
		///   filenames will lead to exceptions. It's too bad, but this is just the way
		///   things are with code pages in zip files. Caveat Emptor.
		/// </para>
		///
		/// <para>
		///   One possible approach for specifying the code page for a given zip file is
		///   to describe the code page in a human-readable form in the Zip comment. For
		///   example, the comment may read "Entries in this archive are encoded in the
		///   Big5 code page".  For maximum interoperability, the zip comment in this
		///   case should be encoded in the default, IBM437 code page.  In this case,
		///   the zip comment is encoded using a different page than the filenames.  To
		///   do this, Specify <c>ProvisionalAlternateEncoding</c> to your desired
		///   region-specific code page, once before adding any entries, and then set
		///   the <see cref="Comment"/> property and reset
		///   <c>ProvisionalAlternateEncoding</c> to IBM437 before calling <c>Close()</c>.
		/// </para>
		/// </remarks>
		[Obsolete("use AlternateEncoding and AlternateEncodingUsage instead.")]
		public System.Text.Encoding ProvisionalAlternateEncoding
		{
			get
			{
				if (_alternateEncodingUsage == ZipOption.AsNecessary)
					return _alternateEncoding;
				return null;
			}
			set
			{
				_alternateEncoding = value;
				_alternateEncodingUsage = ZipOption.AsNecessary;
			}
		}

		/// <summary>
		///   A Text Encoding to use when encoding the filenames and comments for
		///   all the ZipEntry items, during a ZipFile.Save() operation.
		/// </summary>
		/// <remarks>
		///   <para>
		///     Whether the encoding specified here is used during the save depends
		///     on <see cref="AlternateEncodingUsage"/>.
		///   </para>
		/// </remarks>
		public System.Text.Encoding AlternateEncoding
		{
			get
			{
				return _alternateEncoding;
			}
			set
			{
				_alternateEncoding = value;
			}
		}

		/// <summary>
		///   A flag that tells if and when this instance should apply
		///   AlternateEncoding to encode the filenames and comments associated to
		///   of ZipEntry objects contained within this instance.
		/// </summary>
		public ZipOption AlternateEncodingUsage
		{
			get
			{
				return _alternateEncodingUsage;
			}
			set
			{
				_alternateEncodingUsage = value;
			}
		}

		/// <summary>
		/// The default text encoding used in zip archives.  It is numeric 437, also
		/// known as IBM437.
		/// </summary>
		/// <seealso cref="PickGold.Zip.ZipFile.ProvisionalAlternateEncoding"/>
		public static System.Text.Encoding DefaultEncoding
		{
			get
			{
				return System.Text.Encoding.GetEncoding("IBM437");
			}
		}


#if !NETCF
		/// <summary>
		///   The size threshold for an entry, above which a parallel deflate is used.
		/// </summary>
		///
		/// <remarks>
		///
		///   <para>
		///     DotNetZip will use multiple threads to compress any ZipEntry, when
		///     the <c>CompressionMethod</c> is Deflate, and if the entry is
		///     larger than the given size.  Zero means "always use parallel
		///     deflate", while -1 means "never use parallel deflate".
		///   </para>
		///
		///   <para>
		///     If the entry size cannot be known before compression, as with any entry
		///     added via a ZipOutputStream, then Parallel deflate will never be
		///     performed, unless the value of this property is zero.
		///   </para>
		///
		///   <para>
		///     A parallel deflate operations will speed up the compression of
		///     large files, on computers with multiple CPUs or multiple CPU
		///     cores.  For files above 1mb, on a dual core or dual-cpu (2p)
		///     machine, the time required to compress the file can be 70% of the
		///     single-threaded deflate.  For very large files on 4p machines the
		///     compression can be done in 30% of the normal time.  The downside
		///     is that parallel deflate consumes extra memory during the deflate,
		///     and the deflation is slightly less effective.
		///   </para>
		///
		///   <para>
		///     Parallel deflate tends to not be as effective as single-threaded deflate
		///     because the original data stream is split into multiple independent
		///     buffers, each of which is compressed in parallel.  But because they are
		///     treated independently, there is no opportunity to share compression
		///     dictionaries, and additional framing bytes must be added to the output
		///     stream.  For that reason, a deflated stream may be slightly larger when
		///     compressed using parallel deflate, as compared to a traditional
		///     single-threaded deflate. For files of about 512k, the increase over the
		///     normal deflate is as much as 5% of the total compressed size. For larger
		///     files, the difference can be as small as 0.1%.
		///   </para>
		///
		///   <para>
		///     Multi-threaded compression does not give as much an advantage when using
		///     Encryption. This is primarily because encryption tends to slow down
		///     the entire pipeline. Also, multi-threaded compression gives less of an
		///     advantage when using lower compression levels, for example <see
		///     cref="PickGold.Zlib.CompressionLevel.BestSpeed"/>.  You may have to perform
		///     some tests to determine the best approach for your situation.
		///   </para>
		///
		///   <para>
		///     The default value for this property is -1, which means parallel
		///     compression will not be performed unless you set it to zero.
		///   </para>
		///
		/// </remarks>
		public long ParallelDeflateThreshold
		{
			set
			{
				if ((value != 0) && (value != -1) && (value < 64 * 1024))
					throw new ArgumentOutOfRangeException("value must be greater than 64k, or 0, or -1");
				_ParallelDeflateThreshold = value;
			}
			get
			{
				return _ParallelDeflateThreshold;
			}
		}


		/// <summary>
		///   The maximum number of buffer pairs to use when performing
		///   parallel compression.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This property sets an upper limit on the number of memory
		///   buffer pairs to create when performing parallel
		///   compression.  The implementation of the parallel
		///   compression stream allocates multiple buffers to
		///   facilitate parallel compression.  As each buffer fills up,
		///   the stream uses <see
		///   cref="System.Threading.ThreadPool.QueueUserWorkItem(WaitCallback)">
		///   ThreadPool.QueueUserWorkItem()</see> to compress those
		///   buffers in a background threadpool thread. After a buffer
		///   is compressed, it is re-ordered and written to the output
		///   stream.
		/// </para>
		///
		/// <para>
		///   A higher number of buffer pairs enables a higher degree of
		///   parallelism, which tends to increase the speed of compression on
		///   multi-cpu computers.  On the other hand, a higher number of buffer
		///   pairs also implies a larger memory consumption, more active worker
		///   threads, and a higher cpu utilization for any compression. This
		///   property enables the application to limit its memory consumption and
		///   CPU utilization behavior depending on requirements.
		/// </para>
		///
		/// <para>
		///   For each compression "task" that occurs in parallel, there are 2
		///   buffers allocated: one for input and one for output.  This property
		///   sets a limit for the number of pairs.  The total amount of storage
		///   space allocated for buffering will then be (N*S*2), where N is the
		///   number of buffer pairs, S is the size of each buffer (<see
		///   cref="CodecBufferSize"/>).  By default, DotNetZip allocates 4 buffer
		///   pairs per CPU core, so if your machine has 4 cores, and you retain
		///   the default buffer size of 128k, then the
		///   ParallelDeflateOutputStream will use 4 * 4 * 2 * 128kb of buffer
		///   memory in total, or 4mb, in blocks of 128kb.  If you then set this
		///   property to 8, then the number will be 8 * 2 * 128kb of buffer
		///   memory, or 2mb.
		/// </para>
		///
		/// <para>
		///   CPU utilization will also go up with additional buffers, because a
		///   larger number of buffer pairs allows a larger number of background
		///   threads to compress in parallel. If you find that parallel
		///   compression is consuming too much memory or CPU, you can adjust this
		///   value downward.
		/// </para>
		///
		/// <para>
		///   The default value is 16. Different values may deliver better or
		///   worse results, depending on your priorities and the dynamic
		///   performance characteristics of your storage and compute resources.
		/// </para>
		///
		/// <para>
		///   This property is not the number of buffer pairs to use; it is an
		///   upper limit. An illustration: Suppose you have an application that
		///   uses the default value of this property (which is 16), and it runs
		///   on a machine with 2 CPU cores. In that case, DotNetZip will allocate
		///   4 buffer pairs per CPU core, for a total of 8 pairs.  The upper
		///   limit specified by this property has no effect.
		/// </para>
		///
		/// <para>
		///   The application can set this value at any time, but it is
		///   effective only if set before calling
		///   <c>ZipOutputStream.Write()</c> for the first time.
		/// </para>
		/// </remarks>
		///
		/// <seealso cref="ParallelDeflateThreshold"/>
		///
		public int ParallelDeflateMaxBufferPairs
		{
			get
			{
				return _maxBufferPairs;
			}
			set
			{
				if (value < 4)
					throw new ArgumentOutOfRangeException("ParallelDeflateMaxBufferPairs",
												"Value must be 4 or greater.");
				_maxBufferPairs = value;
			}
		}
#endif


		private void InsureUniqueEntry(ZipEntry ze1)
		{
			if (_entriesWritten.ContainsKey(ze1.FileName))
			{
				_exceptionPending = true;
				throw new ArgumentException(String.Format("The entry '{0}' already exists in the zip archive.", ze1.FileName));
			}
		}


		internal Stream OutputStream
		{
			get
			{
				return _outputStream;
			}
		}

		internal String Name
		{
			get
			{
				return _name;
			}
		}

		/// <summary>
		///   Returns true if an entry by the given name has already been written
		///   to the ZipOutputStream.
		/// </summary>
		///
		/// <param name="name">
		///   The name of the entry to scan for.
		/// </param>
		///
		/// <returns>
		/// true if an entry by the given name has already been written.
		/// </returns>
		public bool ContainsEntry(string name)
		{
			return _entriesWritten.ContainsKey(SharedUtilities.NormalizePathForUseInZipFile(name));
		}


		/// <summary>
		///   Write the data from the buffer to the stream.
		/// </summary>
		///
		/// <remarks>
		///   As the application writes data into this stream, the data may be
		///   compressed and encrypted before being written out to the underlying
		///   stream, depending on the settings of the <see cref="CompressionLevel"/>
		///   and the <see cref="Encryption"/> properties.
		/// </remarks>
		///
		/// <param name="buffer">The buffer holding data to write to the stream.</param>
		/// <param name="offset">the offset within that data array to find the first byte to write.</param>
		/// <param name="count">the number of bytes to write.</param>
		public override void Write(byte[] buffer, int offset, int count)
		{
			if (_disposed)
			{
				_exceptionPending = true;
				throw new System.InvalidOperationException("The stream has been closed.");
			}

			if (buffer == null)
			{
				_exceptionPending = true;
				throw new System.ArgumentNullException("buffer");
			}

			if (_currentEntry == null)
			{
				_exceptionPending = true;
				throw new System.InvalidOperationException("You must call PutNextEntry() before calling Write().");
			}

			if (_currentEntry.IsDirectory)
			{
				_exceptionPending = true;
				throw new System.InvalidOperationException("You cannot Write() data for an entry that is a directory.");
			}

			if (_needToWriteEntryHeader)
				_InitiateCurrentEntry(false);

			if (count != 0)
				_entryOutputStream.Write(buffer, offset, count);
		}



		/// <summary>
		///   Specify the name of the next entry that will be written to the zip file.
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   Call this method just before calling <see cref="Write(byte[], int, int)"/>, to
		///   specify the name of the entry that the next set of bytes written to
		///   the <c>ZipOutputStream</c> belongs to. All subsequent calls to <c>Write</c>,
		///   until the next call to <c>PutNextEntry</c>,
		///   will be inserted into the named entry in the zip file.
		/// </para>
		///
		/// <para>
		///   If the <paramref name="entryName"/> used in <c>PutNextEntry()</c> ends in
		///   a slash, then the entry added is marked as a directory. Because directory
		///   entries do not contain data, a call to <c>Write()</c>, before an
		///   intervening additional call to <c>PutNextEntry()</c>, will throw an
		///   exception.
		/// </para>
		///
		/// <para>
		///   If you don't call <c>Write()</c> between two calls to
		///   <c>PutNextEntry()</c>, the first entry is inserted into the zip file as a
		///   file of zero size.  This may be what you want.
		/// </para>
		///
		/// <para>
		///   Because <c>PutNextEntry()</c> closes out the prior entry, if any, this
		///   method may throw if there is a problem with the prior entry.
		/// </para>
		///
		/// <para>
		///   This method returns the <c>ZipEntry</c>.  You can modify public properties
		///   on the <c>ZipEntry</c>, such as <see cref="ZipEntry.Encryption"/>, <see
		///   cref="ZipEntry.Password"/>, and so on, until the first call to
		///   <c>ZipOutputStream.Write()</c>, or until the next call to
		///   <c>PutNextEntry()</c>.  If you modify the <c>ZipEntry</c> <em>after</em>
		///   having called <c>Write()</c>, you may get a runtime exception, or you may
		///   silently get an invalid zip archive.
		/// </para>
		///
		/// </remarks>
		///
		/// <example>
		///
		///   This example shows how to create a zip file, using the
		///   <c>ZipOutputStream</c> class.
		///
		/// <code>
		/// private void Zipup()
		/// {
		///     using (FileStream fs raw = File.Open(_outputFileName, FileMode.Create, FileAccess.ReadWrite ))
		///     {
		///         using (var output= new ZipOutputStream(fs))
		///         {
		///             output.Password = "VerySecret!";
		///             output.Encryption = EncryptionAlgorithm.WinZipAes256;
		///             output.PutNextEntry("entry1.txt");
		///             byte[] buffer= System.Text.Encoding.ASCII.GetBytes("This is the content for entry #1.");
		///             output.Write(buffer,0,buffer.Length);
		///             output.PutNextEntry("entry2.txt");  // this will be zero length
		///             output.PutNextEntry("entry3.txt");
		///             buffer= System.Text.Encoding.ASCII.GetBytes("This is the content for entry #3.");
		///             output.Write(buffer,0,buffer.Length);
		///         }
		///     }
		/// }
		/// </code>
		/// </example>
		///
		/// <param name="entryName">
		///   The name of the entry to be added, including any path to be used
		///   within the zip file.
		/// </param>
		///
		/// <returns>
		///   The ZipEntry created.
		/// </returns>
		///
		public ZipEntry PutNextEntry(String entryName)
		{
			if (String.IsNullOrEmpty(entryName))
				throw new ArgumentNullException("entryName");

			if (_disposed)
			{
				_exceptionPending = true;
				throw new System.InvalidOperationException("The stream has been closed.");
			}

			_FinishCurrentEntry();
			_currentEntry = ZipEntry.CreateForZipOutputStream(entryName);
			_currentEntry._container = new ZipContainer(this);
			_currentEntry._BitField |= 0x0008;  // workitem 8932
			_currentEntry.SetEntryTimes(DateTime.Now, DateTime.Now, DateTime.Now);
			_currentEntry.CompressionLevel = this.CompressionLevel;
			_currentEntry.CompressionMethod = this.CompressionMethod;
			_currentEntry.Password = _password; // workitem 13909
			_currentEntry.Encryption = this.Encryption;
			// workitem 12634
			_currentEntry.AlternateEncoding = this.AlternateEncoding;
			_currentEntry.AlternateEncodingUsage = this.AlternateEncodingUsage;

			if (entryName.EndsWith("/")) _currentEntry.MarkAsDirectory();

			_currentEntry.EmitTimesInWindowsFormatWhenSaving = ((_timestamp & ZipEntryTimestamp.Windows) != 0);
			_currentEntry.EmitTimesInUnixFormatWhenSaving = ((_timestamp & ZipEntryTimestamp.Unix) != 0);
			InsureUniqueEntry(_currentEntry);
			_needToWriteEntryHeader = true;

			return _currentEntry;
		}



		private void _InitiateCurrentEntry(bool finishing)
		{
			// If finishing==true, this means we're initiating the entry at the time of
			// Close() or PutNextEntry().  If this happens, it means no data was written
			// for the entry - Write() was never called.  (The usual case us to call
			// _InitiateCurrentEntry(bool) from within Write().)  If finishing==true,
			// the entry could be either a zero-byte file or a directory.

			_entriesWritten.Add(_currentEntry.FileName, _currentEntry);
			_entryCount++; // could use _entriesWritten.Count, but I don't want to incur
			// the cost.

			if (_entryCount > 65534 && _zip64 == Zip64Option.Never)
			{
				_exceptionPending = true;
				throw new System.InvalidOperationException("Too many entries. Consider setting ZipOutputStream.EnableZip64.");
			}

			// Write out the header.
			//
			// If finishing, and encryption is in use, then we don't want to emit the
			// normal encryption header.  Signal that with a cycle=99 to turn off
			// encryption for zero-byte entries or directories.
			//
			// If finishing, then we know the stream length is zero.  Else, unknown
			// stream length.  Passing stream length == 0 allows an optimization so as
			// not to setup an encryption or deflation stream, when stream length is
			// zero.

			_currentEntry.WriteHeader(_outputStream, finishing ? 99 : 0);
			_currentEntry.StoreRelativeOffset();

			if (!_currentEntry.IsDirectory)
			{
				_currentEntry.WriteSecurityMetadata(_outputStream);
				_currentEntry.PrepOutputStream(_outputStream,
											   finishing ? 0 : -1,
											   out _outputCounter,
											   out _encryptor,
											   out _deflater,
											   out _entryOutputStream);
			}
			_needToWriteEntryHeader = false;
		}



		private void _FinishCurrentEntry()
		{
			if (_currentEntry != null)
			{
				if (_needToWriteEntryHeader)
					_InitiateCurrentEntry(true); // an empty entry - no writes

				_currentEntry.FinishOutputStream(_outputStream, _outputCounter, _encryptor, _deflater, _entryOutputStream);
				_currentEntry.PostProcessOutput(_outputStream);
				// workitem 12964
				if (_currentEntry.OutputUsedZip64 != null)
					_anyEntriesUsedZip64 |= _currentEntry.OutputUsedZip64.Value;

				// reset all the streams
				_outputCounter = null; _encryptor = _deflater = null; _entryOutputStream = null;
			}
		}



		/// <summary>
		/// Dispose the stream
		/// </summary>
		///
		/// <remarks>
		/// <para>
		///   This method writes the Zip Central directory, then closes the stream.  The
		///   application must call Dispose() (or Close) in order to produce a valid zip file.
		/// </para>
		///
		/// <para>
		///   Typically the application will call <c>Dispose()</c> implicitly, via a <c>using</c>
		///   statement in C#, or a <c>Using</c> statement in VB.
		/// </para>
		///
		/// </remarks>
		///
		/// <param name="disposing">set this to true, always.</param>
		protected override void Dispose(bool disposing)
		{
			if (_disposed) return;

			if (disposing) // not called from finalizer
			{
				// handle pending exceptions
				if (!_exceptionPending)
				{
					_FinishCurrentEntry();
					_directoryNeededZip64 = ZipOutput.WriteCentralDirectoryStructure(_outputStream,
																					 _entriesWritten.Values,
																					 1, // _numberOfSegmentsForMostRecentSave,
																					 _zip64,
																					 Comment,
																					 new ZipContainer(this));
					Stream wrappedStream = null;
					CountingStream cs = _outputStream as CountingStream;
					if (cs != null)
					{
						wrappedStream = cs.WrappedStream;
#if NETCF
                    cs.Close();
#else
						cs.Dispose();
#endif
					}
					else
					{
						wrappedStream = _outputStream;
					}

					if (!_leaveUnderlyingStreamOpen)
					{
#if NETCF
                    wrappedStream.Close();
#else
						wrappedStream.Dispose();
#endif
					}
					_outputStream = null;
				}
			}
			_disposed = true;
		}



		/// <summary>
		/// Always returns false.
		/// </summary>
		public override bool CanRead { get { return false; } }

		/// <summary>
		/// Always returns false.
		/// </summary>
		public override bool CanSeek { get { return false; } }

		/// <summary>
		/// Always returns true.
		/// </summary>
		public override bool CanWrite { get { return true; } }

		/// <summary>
		/// Always returns a NotSupportedException.
		/// </summary>
		public override long Length { get { throw new NotSupportedException(); } }

		/// <summary>
		/// Setting this property always returns a NotSupportedException. Getting it
		/// returns the value of the Position on the underlying stream.
		/// </summary>
		public override long Position
		{
			get { return _outputStream.Position; }
			set { throw new NotSupportedException(); }
		}

		/// <summary>
		/// This is a no-op.
		/// </summary>
		public override void Flush() { }

		/// <summary>
		/// This method always throws a NotSupportedException.
		/// </summary>
		/// <param name="buffer">ignored</param>
		/// <param name="offset">ignored</param>
		/// <param name="count">ignored</param>
		/// <returns>nothing</returns>
		public override int Read(byte[] buffer, int offset, int count)
		{
			throw new NotSupportedException("Read");
		}

		/// <summary>
		/// This method always throws a NotSupportedException.
		/// </summary>
		/// <param name="offset">ignored</param>
		/// <param name="origin">ignored</param>
		/// <returns>nothing</returns>
		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException("Seek");
		}

		/// <summary>
		/// This method always throws a NotSupportedException.
		/// </summary>
		/// <param name="value">ignored</param>
		public override void SetLength(long value)
		{
			throw new NotSupportedException();
		}


		private EncryptionAlgorithm _encryption;
		private ZipEntryTimestamp _timestamp;
		internal String _password;
		private String _comment;
		private Stream _outputStream;
		private ZipEntry _currentEntry;
		internal Zip64Option _zip64;
		private Dictionary<String, ZipEntry> _entriesWritten;
		private int _entryCount;
		private ZipOption _alternateEncodingUsage = ZipOption.Never;
		private System.Text.Encoding _alternateEncoding
			= System.Text.Encoding.GetEncoding("IBM437"); // default = IBM437

		private bool _leaveUnderlyingStreamOpen;
		private bool _disposed;
		private bool _exceptionPending; // **see note below
		private bool _anyEntriesUsedZip64, _directoryNeededZip64;
		private CountingStream _outputCounter;
		private Stream _encryptor;
		private Stream _deflater;
		private CalculatorStream _entryOutputStream;
		private bool _needToWriteEntryHeader;
		private string _name;
		private bool _DontIgnoreCase;
#if !NETCF
		internal PickGold.Zlib.ParallelDeflateOutputStream ParallelDeflater;
		private long _ParallelDeflateThreshold;
		private int _maxBufferPairs = 16;
#endif

		// **Note regarding exceptions:

		// When ZipOutputStream is employed within a using clause, which
		// is the typical scenario, and an exception is thrown within
		// the scope of the using, Close()/Dispose() is invoked
		// implicitly before processing the initial exception.  In that
		// case, _exceptionPending is true, and we don't want to try to
		// write anything in the Close/Dispose logic.  Doing so can
		// cause additional exceptions that mask the original one. So,
		// the _exceptionPending flag is used to track that, and to
		// allow the original exception to be propagated to the
		// application without extra "noise."

	}

	internal class ZipContainer
	{
		private ZipFile _zf;
		private ZipOutputStream _zos;
		private ZipInputStream _zis;

		public ZipContainer(Object o)
		{
			_zf = (o as ZipFile);
			_zos = (o as ZipOutputStream);
			_zis = (o as ZipInputStream);
		}

		public ZipFile ZipFile
		{
			get { return _zf; }
		}

		public ZipOutputStream ZipOutputStream
		{
			get { return _zos; }
		}

		public string Name
		{
			get
			{
				if (_zf != null) return _zf.Name;
				if (_zis != null) throw new NotSupportedException();
				return _zos.Name;
			}
		}

		public string Password
		{
			get
			{
				if (_zf != null) return _zf._Password;
				if (_zis != null) return _zis._Password;
				return _zos._password;
			}
		}

		public Zip64Option Zip64
		{
			get
			{
				if (_zf != null) return _zf._zip64;
				if (_zis != null) throw new NotSupportedException();
				return _zos._zip64;
			}
		}

		public int BufferSize
		{
			get
			{
				if (_zf != null) return _zf.BufferSize;
				if (_zis != null) throw new NotSupportedException();
				return 0;
			}
		}

#if !NETCF
		public PickGold.Zlib.ParallelDeflateOutputStream ParallelDeflater
		{
			get
			{
				if (_zf != null) return _zf.ParallelDeflater;
				if (_zis != null) return null;
				return _zos.ParallelDeflater;
			}
			set
			{
				if (_zf != null) _zf.ParallelDeflater = value;
				else if (_zos != null) _zos.ParallelDeflater = value;
			}
		}

		public long ParallelDeflateThreshold
		{
			get
			{
				if (_zf != null) return _zf.ParallelDeflateThreshold;
				return _zos.ParallelDeflateThreshold;
			}
		}
		public int ParallelDeflateMaxBufferPairs
		{
			get
			{
				if (_zf != null) return _zf.ParallelDeflateMaxBufferPairs;
				return _zos.ParallelDeflateMaxBufferPairs;
			}
		}
#endif

		public int CodecBufferSize
		{
			get
			{
				if (_zf != null) return _zf.CodecBufferSize;
				if (_zis != null) return _zis.CodecBufferSize;
				return _zos.CodecBufferSize;
			}
		}

		public PickGold.Zlib.CompressionStrategy Strategy
		{
			get
			{
				if (_zf != null) return _zf.Strategy;
				return _zos.Strategy;
			}
		}

		public Zip64Option UseZip64WhenSaving
		{
			get
			{
				if (_zf != null) return _zf.UseZip64WhenSaving;
				return _zos.EnableZip64;
			}
		}

		public System.Text.Encoding AlternateEncoding
		{
			get
			{
				if (_zf != null) return _zf.AlternateEncoding;
				if (_zos != null) return _zos.AlternateEncoding;
				return null;
			}
		}
		public System.Text.Encoding DefaultEncoding
		{
			get
			{
				if (_zf != null) return ZipFile.DefaultEncoding;
				if (_zos != null) return ZipOutputStream.DefaultEncoding;
				return null;
			}
		}
		public ZipOption AlternateEncodingUsage
		{
			get
			{
				if (_zf != null) return _zf.AlternateEncodingUsage;
				if (_zos != null) return _zos.AlternateEncodingUsage;
				return ZipOption.Never; // n/a
			}
		}

		public Stream ReadStream
		{
			get
			{
				if (_zf != null) return _zf.ReadStream;
				return _zis.ReadStream;
			}
		}
	}

}
